Respiratory Protection Against Airborne Bacteria in Dental Clinics During Cleaning Procedures

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Background and Objectives: Turbine burs, water-air sprays and other aerosol forming instruments used in dental clinics during dental cleaning procedures can release oral bacteria including potential pathogens in clinic air. The employees mostly use dental surgical masks to prevent exposure to these airborne bacteria. FDA approval of surgical masks depends on fluid resistance, filter efficiency, differential pressure, and flammability of the mask. Real-time protection offered by surgical masks against airborne bacteria in dental clinic occupational/environmental setting, however, is currently unknown. The objective of this study was to assess this real-time protection factor using a manikin-based bioaerosol sampling set-up during actual dental cleaning procedures.

Methods: Protection factors offered by dental surgical masks were determined by using a manikin donned with a dental surgical mask where air samples were collected from inside and outside of the mask during 15 cleaning procedures (n = 90) using filter cassettes loaded with gelatin filters and compared. Aliquots of gelatin filter extract suspensions were immediately cultivated in triplicate on tryptic soy agar and incubated at 30 ± 2°C for 72 h for isolating mesophilic bacterial species. The colony counts were converted into bacterial airborne concentrations (CFU/m(3)).

Results: Overall, the concentrations of airborne culturable bacteria outside and inside the surgical masks were 8619 ± 8548 CFU/m(3) and 4848 ± 5057 CFU/m(3), respectively.

Conclusions: Dental clinic employees are exposed to elevated levels of airborne bacteria even during their use of surgical masks throughout dental cleaning procedures and use of surgical masks provide approx. 56% protection against airborne bacteria.


American Public Health Association Annual Meeting (APHA)


Denver, CO